bug#53355: guix shell --check: confusing error message

bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi,

I've grown so used to using "guix environment," I thought I'd try out
"guix shell."  It looks pretty neat!  It's good to try to improve the
CLI.

However, when I tried "guix shell," I quickly observed this confusing
behavior:

--8<---------------cut here---------------start------------->8---
[130] marusich@suzaku:~/guix-master
$ guix shell --container --check -D guix
guix shell: checking the environment variables visible from shell '/bin/bash'...
guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] marusich@suzaku:~/guix-master
$ env | grep PKG_CONF
[1] marusich@suzaku:~/guix-master
$ guix shell --check -D guix
guix shell: checking the environment variables visible from shell '/bin/bash'...
guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] marusich@suzaku:~/guix-master
$ guix shell -D guix
[0] [env] marusich@suzaku:~/guix-master
$ env | grep PKG
PKG_CONFIG_PATH=/gnu/store/qr79b2m6cfdj8ar7g0psqg4hglm6djfm-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$
exit
[0] marusich@suzaku:~/guix-master
$ guix shell --container -D guix
marusich@suzaku ~/guix-master [env]$ env | grep PKG
PKG_CONFIG_PATH=/gnu/store/qr79b2m6cfdj8ar7g0psqg4hglm6djfm-profile/lib/pkgconfig
marusich@suzaku ~/guix-master [env]$
--8<---------------cut here---------------end--------------->8---

I found the following things to be confusing:

(1) The error message claims that PKG_CONFIG_PATH is "missing from shell
environment."  However, it seems to be present when I run "env".

(2) It says I can avoid the problem by passing the `--container' option,
but even when I do that, the problem seems to persist.  If that is
expected behavior, then perhaps the wording should be changed to
something less certain, such as "you might be able to avoid the
problem".  It does not seem to be the case that I can avoid the problem
by passing the `--container' option in this case.

What's really going on here?  It's good to be able to look at this
feature with the eyes of a newbie, since I'm very used to using "guix
environment", but "guix shell" is totally new to me.  I thought it would
be a good opportunity to provide feedback.

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

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Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> [130] marusich@suzaku:~/guix-master
> $ guix shell --container --check -D guix
> guix shell: checking the environment variables visible from shell '/bin/bash'...
> guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment

[...]

> I found the following things to be confusing:
>
> (1) The error message claims that PKG_CONFIG_PATH is "missing from shell
> environment."  However, it seems to be present when I run "env".
>
> (2) It says I can avoid the problem by passing the `--container' option,
> but even when I do that, the problem seems to persist.  If that is
> expected behavior, then perhaps the wording should be changed to
> something less certain, such as "you might be able to avoid the
> problem".  It does not seem to be the case that I can avoid the problem
> by passing the `--container' option in this case.

What’s confusing is that ‘--check’ does the same job whether or not
‘--container’ is passed: it checks the behavior of your shell *outside*
a container.

I think ‘--check’ should just do nothing when ‘--container’ is used,
possibly emitting a warning saying it’s not doing anything (patch
below).

Now, the diagnostic is hopefully correct if you use, say, ‘--pure’
instead of ‘--container’.  Could you check whether this is the case?

Thanks,
Ludo’.


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diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 510cee727f..ec071402f4 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2014, 2015, 2018 David Thompson <davet@gnu.org>
-;;; Copyright © 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015-2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2018 Mike Gerwitz <mtg@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -975,7 +975,10 @@ (define manifest
 
                   (mwhen (assoc-ref opts 'check?)
                     (return
-                     (validate-child-shell-environment profile manifest)))
+                     (if container?
+                         (warning (G_ "'--check' is unnecessary \
+when using '--container'; doing nothing~%"))
+                         (validate-child-shell-environment profile manifest))))
 
                   (cond
                    ((assoc-ref opts 'search-paths)

bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi Ludo,

Thank you for the response!

Ludovic Courtès <ludo@gnu.org> writes:

> What’s confusing is that ‘--check’ does the same job whether or not
> ‘--container’ is passed: it checks the behavior of your shell *outside*
> a container.
>
> I think ‘--check’ should just do nothing when ‘--container’ is used,
> possibly emitting a warning saying it’s not doing anything (patch
> below).
>
> Now, the diagnostic is hopefully correct if you use, say, ‘--pure’
> instead of ‘--container’.  Could you check whether this is the case?

That sounds reasonable.  I tested your patch.  It now correctly emits a
warning when both --container and --check are provided.  However, I now
see that the issue occurs even when --container is omitted.  So it seems
like something else might be going on.

Below, I'll provide details of what I did to test your patch.

In one test, I committed your change locally and did "guix pull" to
install the patched Guix into ~/tmpguixprofile.  I then tried using it:

--8<---------------cut here---------------start------------->8---
[0] marusich@suzaku:~/guix-master
$ env -i bash
[0] marusich@suzaku:/home/marusich/guix-master
$ activate-profile ~/tmpguixprofile
[0] marusich@suzaku:/home/marusich/guix-master
$ which guix
/home/marusich/tmpguixprofile/bin/guix
--8<---------------cut here---------------end--------------->8---

First, I tried without --pure or --container.  Below, you can see that
it claims LIBRARY_PATH is missing, but it does not seem to be missing:

--8<---------------cut here---------------start------------->8---
[0] marusich@suzaku:/home/marusich/guix-master
$ guix shell --check -D guix
guix shell: checking the environment variables visible from shell '/bin/sh'...
guix shell: warning: variable 'LIBRARY_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] marusich@suzaku:/home/marusich/guix-master
$ env | grep LIBRARY_PATH
[1] marusich@suzaku:/home/marusich/guix-master
$ guix shell -D guix
[0] \u@\H:\w\n$ env | grep LIBRARY_PATH
LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib
--8<---------------cut here---------------end--------------->8---

Next, I tried with --container - you can see it works as intended:

--8<---------------cut here---------------start------------->8---
[0] marusich@suzaku:/home/marusich/guix-master
$ guix shell --container --check -D guix
guix shell: warning: '--check' is unnecessary when using '--container'; doing nothing
--8<---------------cut here---------------end--------------->8---

Next, I tried with --pure and --check - once again, it claims
LIBRARY_PATH is missing, even though it does not seem to be missing:

--8<---------------cut here---------------start------------->8---
[0] marusich@suzaku:/home/marusich/guix-master
$ guix shell --pure --check -D guix
guix shell: checking the environment variables visible from shell '/bin/sh'...
guix shell: warning: variable 'LIBRARY_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] marusich@suzaku:/home/marusich/guix-master
$ env | grep LIBRARY_PATH
[1] marusich@suzaku:/home/marusich/guix-master
$ guix shell --pure -D guix
$ env | grep LIBRARY_PATH
LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib
--8<---------------cut here---------------end--------------->8---

A similar error message occurs if I try the same steps from a checkout
using pre-inst-env.  However, in that case the offending environment
variable is different (PKG_CONFIG_PATH in this case):

--8<---------------cut here---------------start------------->8---
[0] marusich@suzaku:~/guix-master
$ guix environment guix
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
guix shell: checking the environment variables visible from shell '/bin/bash'...
guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --pure -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
guix shell: checking the environment variables visible from shell '/bin/bash'...
guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --container -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
guix shell: warning: '--check' is unnecessary when using '--container'; doing nothing
in env, PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
in env, PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --pure -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
in env, PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --container -D guix -- bash -c 'echo in env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"'
in env, PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$ echo out of env, PKG_CONFIG_PATH="$PKG_CONFIG_PATH"
out of env, PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig
[0] [env] marusich@suzaku:~/guix-master
$
--8<---------------cut here---------------end--------------->8---

It seems this issue happens regardless of whether I use pre-inst-env or
run Guix from a "guix pull" installation.

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:
>
>> What’s confusing is that ‘--check’ does the same job whether or not
>> ‘--container’ is passed: it checks the behavior of your shell *outside*
>> a container.
>>
>> I think ‘--check’ should just do nothing when ‘--container’ is used,
>> possibly emitting a warning saying it’s not doing anything (patch
>> below).
>>
>> Now, the diagnostic is hopefully correct if you use, say, ‘--pure’
>> instead of ‘--container’.  Could you check whether this is the case?
>
> That sounds reasonable.  I tested your patch.  It now correctly emits a
> warning when both --container and --check are provided.

Great, I’ll commit it.

> First, I tried without --pure or --container.  Below, you can see that
> it claims LIBRARY_PATH is missing, but it does not seem to be missing:

[...]

> Next, I tried with --pure and --check - once again, it claims
> LIBRARY_PATH is missing, even though it does not seem to be missing:

It looks like the shell-check machinery is misdiagnosing things, as
Vagrant reported in <https://issues.guix.gnu.org/51466> (is this on
Debian too?).

Could you try the debugging tricks I proposed there?

TIA,
Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi,

I also observed this bug and reported it as 53355.  I tried to search
for bugs, but I didn't find this bug report until Ludo mentioned it.  I
think it's probably the same bug, so I've merged them.

Ludovic Courtès <ludo@gnu.org> writes:

> It looks like the shell-check machinery is misdiagnosing things, as
> Vagrant reported in <https://issues.guix.gnu.org/51466> (is this on
> Debian too?).

Yes, it's also Debian.  Debian Bullseye.  I've also verified that
similar behavior occurs on Fedora, although the problematic env vars are
different.  I tried fiddling with SHELL like Vagrant did, but I couldn't
make the error go away like he did.  Maybe I did something differently.

> Could you try the debugging tricks I proposed there?

Sure thing!  Thank you for taking the time to make the patch, even
though it was simple.  Here is the result on my Debian Bullseye ppc64el
system:

--8<---------------cut here---------------start------------->8---
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --pure --development guix
guix shell: checking the environment variables visible from shell '/bin/sh'...

;;; (dropped "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit" #<vlist ()>)

;;; (variable "$ LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib" "$ LIBRARY_PATH")

;;; (variable "C_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "C_INCLUDE_PATH")

;;; (variable "USER=marusich" "USER")

;;; (variable "GUIX_LOCPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/locale" "GUIX_LOCPATH")

;;; (variable "HOME=/home/marusich" "HOME")

;;; (variable "GUILE_LOAD_COMPILED_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/guile/3.0/site-ccache:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_COMPILED_PATH")

;;; (variable "CPLUS_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include/c++:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "CPLUS_INCLUDE_PATH")

;;; (variable "INFOPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/info" "INFOPATH")

;;; (variable "LOGNAME=marusich" "LOGNAME")

;;; (variable "PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig" "PKG_CONFIG_PATH")

;;; (variable "TERM=screen.xterm-256color" "TERM")

;;; (variable "ACLOCAL_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/aclocal" "ACLOCAL_PATH")

;;; (variable "PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/sbin" "PATH")

;;; (variable "GUIX_ENVIRONMENT=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile" "GUIX_ENVIRONMENT")

;;; (variable "GUILE_LOAD_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_PATH")

;;; (variable "PWD=/home/marusich/guix-master" "PWD")
guix shell: warning: variable 'LIBRARY_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] [env] marusich@suzaku:~/guix-master
$
--8<---------------cut here---------------end--------------->8---

The presence of the "$" in front of LIBRARY_PATH seems suspicious:

  ;;; (variable "$ LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib" "$ LIBRARY_PATH")

I'm not sure why the "$" is being added.  I tried various things to
remove it.  I tried explicitly setting PS1 to an empty string in my
~/.bashrc.  I also tried setting it explicitly to an empty string in
/etc/profile.  Maybe if we can figure out where that "$ " prefix is
coming from, we can resolve this issue?

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

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Hi Chris,

Thanks for testing!

Chris Marusich <cmmarusich@gmail.com> skribis:

> The presence of the "$" in front of LIBRARY_PATH seems suspicious:
>
>   ;;; (variable "$ LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib" "$ LIBRARY_PATH")
>
> I'm not sure why the "$" is being added.  I tried various things to
> remove it.  I tried explicitly setting PS1 to an empty string in my
> ~/.bashrc.  I also tried setting it explicitly to an empty string in
> /etc/profile.  Maybe if we can figure out where that "$ " prefix is
> coming from, we can resolve this issue?

How about this:


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index ec071402f4..ac2c79ab65 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -420,7 +420,7 @@ (define script
     ;; Script to obtain the list of environment variable values.  On a POSIX
     ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
     ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
 
   (define lines
     (match (primitive-fork)

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?

Thanks,
Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi Ludo,

Ludovic Courtès <ludo@gnu.org> writes:

> How about this:
>
> diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
> index ec071402f4..ac2c79ab65 100644
> --- a/guix/scripts/environment.scm
> +++ b/guix/scripts/environment.scm
> @@ -420,7 +420,7 @@ (define script
>      ;; Script to obtain the list of environment variable values.  On a POSIX
>      ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
>      ;; 'set' truncates values and prints them in a different format.)
> -    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
> +    "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
>  
>    (define lines
>      (match (primitive-fork)

Unfortunately, this doesn't quite work.  I tried this patch:

--8<---------------cut here---------------start------------->8---
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 510cee727f..4399a5dd04 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -420,7 +420,7 @@ (define script
     ;; Script to obtain the list of environment variable values.  On a POSIX
     ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
     ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
 
   (define lines
     (match (primitive-fork)
@@ -440,7 +440,7 @@ (define lines
               (result (begin
                         (display script port)
                         (let loop ((lines '()))
-                          (match (read-line port)
+                          (match (pk 'read-line (read-line port))
                             ((? eof-object?) (reverse lines))
                             ("GUIX-CHECK-DONE\r"
                              (display "done\n" port)
@@ -458,10 +458,10 @@ (define lines
           ;; but it also truncates values anyway, so don't try to support it.
           (let ((index (string-index line #\=)))
             (if index
-                (vhash-cons (string-take line index)
+                (vhash-cons (pk 'variable line (string-take line index))
                             (string-drop line (+ 1 index))
                             table)
-                table)))
+                (pk 'dropped line table))))
         vlist-null
         lines))
--8<---------------cut here---------------end--------------->8---

Here is the output:

--8<---------------cut here---------------start------------->8---
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --pure --development guix
guix shell: checking the environment variables visible from shell '/bin/bash'...

;;; (read-line "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\r")

;;; (read-line "\x1b[?2004h[0] [env] marusich@suzaku:~/guix-master\r\r")

;;; (read-line "$ PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\r")

;;; (read-line "\x1b[?2004l\rPKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig\r")

;;; (read-line "PWD=/home/marusich/guix-master\r")

;;; (read-line "LOGNAME=marusich\r")

;;; (read-line "GUILE_LOAD_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0\r")

;;; (read-line "HOME=/home/marusich\r")

;;; (read-line "LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:\r")

;;; (read-line "GUILE_LOAD_COMPILED_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/guile/3.0/site-ccache:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0\r")

;;; (read-line "INFOPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/info\r")

;;; (read-line "TERM=screen.xterm-256color\r")

;;; (read-line "CPLUS_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include/c++:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include\r")

;;; (read-line "ACLOCAL_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/aclocal\r")

;;; (read-line "USER=marusich\r")

;;; (read-line "LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib\r")

;;; (read-line "SHLVL=1\r")

;;; (read-line "GUIX_LOCPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/locale\r")

;;; (read-line "GUIX_ENVIRONMENT=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile\r")

;;; (read-line "PS1=\r")

;;; (read-line "PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/sbin\r")

;;; (read-line "C_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include\r")

;;; (read-line "_=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin/env\r")

;;; (read-line "GUIX-CHECK-DONE\r")

;;; (variable "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit" "PS1")

;;; (dropped "\x1b[?2004h[0] [env] marusich@suzaku:~/guix-master\r" #<vhash 2b482ca0 1 pairs>)

;;; (variable "$ PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit" "$ PS1")

;;; (variable "\x1b[?2004l\rPKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig" "\x1b[?2004l\rPKG_CONFIG_PATH")

;;; (variable "PWD=/home/marusich/guix-master" "PWD")

;;; (variable "LOGNAME=marusich" "LOGNAME")

;;; (variable "GUILE_LOAD_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_PATH")

;;; (variable "HOME=/home/marusich" "HOME")

;;; (variable "LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:" "LS_COLORS")

;;; (variable "GUILE_LOAD_COMPILED_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/guile/3.0/site-ccache:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_COMPILED_PATH")

;;; (variable "INFOPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/info" "INFOPATH")

;;; (variable "TERM=screen.xterm-256color" "TERM")

;;; (variable "CPLUS_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include/c++:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "CPLUS_INCLUDE_PATH")

;;; (variable "ACLOCAL_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/aclocal" "ACLOCAL_PATH")

;;; (variable "USER=marusich" "USER")

;;; (variable "LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib" "LIBRARY_PATH")

;;; (variable "SHLVL=1" "SHLVL")

;;; (variable "GUIX_LOCPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/locale" "GUIX_LOCPATH")

;;; (variable "GUIX_ENVIRONMENT=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile" "GUIX_ENVIRONMENT")

;;; (variable "PS1=" "PS1")

;;; (variable "PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/sbin" "PATH")

;;; (variable "C_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "C_INCLUDE_PATH")

;;; (variable "_=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin/env" "_")
guix shell: warning: variable 'PKG_CONFIG_PATH' is missing from shell environment
hint: One or more environment variables have a different value in the shell than
the one we set.  This means that you may find yourself running code in an
environment different from the one you asked Guix to prepare.

This usually indicates that your shell startup files are unexpectedly
modifying those environment variables.  For example, if you are using Bash,
make sure that environment variables are set or modified in
`~/.bash_profile' and _not_ in `~/.bashrc'.  For more information on Bash
startup files, run:

     info "(bash) Bash Startup Files"

Alternatively, you can avoid the problem by passing the `--container' or
`-C' option.  That will give you a fully isolated environment running in a
"container", immune to the issue described above.

[1] [env] marusich@suzaku:~/guix-master
$ 
--8<---------------cut here---------------end--------------->8---

Most of the interesting stuff happened in the first few lines:

--8<---------------cut here---------------start------------->8---
;;; (read-line "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\r")

;;; (read-line "\x1b[?2004h[0] [env] marusich@suzaku:~/guix-master\r\r")

;;; (read-line "$ PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\r")

;;; (read-line "\x1b[?2004l\rPKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig\r")
--8<---------------cut here---------------end--------------->8---

As you can see, nothing good is happening when the code parses this
later on:

--8<---------------cut here---------------start------------->8---
;;; (variable "PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit" "PS1")

;;; (dropped "\x1b[?2004h[0] [env] marusich@suzaku:~/guix-master\r" #<vhash 2b482ca0 1 pairs>)

;;; (variable "$ PS1=; env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit" "$ PS1")

;;; (variable "\x1b[?2004l\rPKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig" "\x1b[?2004l\rPKG_CONFIG_PATH")
--8<---------------cut here---------------end--------------->8---

Although I'm sure you see it, for clarity I will explain why the above
is bad: The first variable was actually just the entire script being
echoed back; it is not actually an environment variable.  The second
variable "$ PS1" is also not really an environment variable.  And the
variable "\x1b[?2004l\rPKG_CONFIG_PATH", again, appears to contain
garbage at the start, probably from my PS1 value.

Basically, I think we can work around these issues if we just read and
discard all that junk at the start.  I wasn't able to figure out a
graceful way to force that to happen, but I did find that simply
printing a few lines at the start of the script was good enough to work
around the issue on my computer.  Here's my proposed patch, with
debugging statements included:

--8<---------------cut here---------------start------------->8---
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 510cee727f..35669b39cd 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -420,7 +420,8 @@ (define script
     ;; Script to obtain the list of environment variable values.  On a POSIX
     ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
     ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    "PS1=; for i in 1 2 3; do echo GUIX_FLUSH_$i; done; \
+env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
 
   (define lines
     (match (primitive-fork)
@@ -439,8 +440,10 @@ (define lines
        (let* ((port   (fdopen controller "r+l"))
               (result (begin
                         (display script port)
+                        (while (not (string=? "GUIX_FLUSH_3\r"
+                                              (read-line port))))
                         (let loop ((lines '()))
-                          (match (read-line port)
+                          (match (pk 'read-line (read-line port))
                             ((? eof-object?) (reverse lines))
                             ("GUIX-CHECK-DONE\r"
                              (display "done\n" port)
@@ -458,10 +461,10 @@ (define lines
           ;; but it also truncates values anyway, so don't try to support it.
           (let ((index (string-index line #\=)))
             (if index
-                (vhash-cons (string-take line index)
+                (vhash-cons (pk 'variable line (string-take line index))
                             (string-drop line (+ 1 index))
                             table)
-                table)))
+                (pk 'dropped line table))))
         vlist-null
         lines))
 
--8<---------------cut here---------------end--------------->8---

And here's the output:

--8<---------------cut here---------------start------------->8---
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --pure --development guix
guix shell: checking the environment variables visible from shell '/bin/bash'...

;;; (read-line "PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig\r")

;;; (read-line "PWD=/home/marusich/guix-master\r")

;;; (read-line "LOGNAME=marusich\r")

;;; (read-line "GUILE_LOAD_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0\r")

;;; (read-line "HOME=/home/marusich\r")

;;; (read-line "LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:\r")

;;; (read-line "GUILE_LOAD_COMPILED_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/guile/3.0/site-ccache:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0\r")

;;; (read-line "INFOPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/info\r")

;;; (read-line "TERM=screen.xterm-256color\r")

;;; (read-line "CPLUS_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include/c++:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include\r")

;;; (read-line "ACLOCAL_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/aclocal\r")

;;; (read-line "USER=marusich\r")

;;; (read-line "LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib\r")

;;; (read-line "SHLVL=1\r")

;;; (read-line "GUIX_LOCPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/locale\r")

;;; (read-line "GUIX_ENVIRONMENT=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile\r")

;;; (read-line "PS1=\r")

;;; (read-line "PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/sbin\r")

;;; (read-line "C_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include\r")

;;; (read-line "_=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin/env\r")

;;; (read-line "GUIX-CHECK-DONE\r")

;;; (variable "PKG_CONFIG_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/pkgconfig" "PKG_CONFIG_PATH")

;;; (variable "PWD=/home/marusich/guix-master" "PWD")

;;; (variable "LOGNAME=marusich" "LOGNAME")

;;; (variable "GUILE_LOAD_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_PATH")

;;; (variable "HOME=/home/marusich" "HOME")

;;; (variable "LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:" "LS_COLORS")

;;; (variable "GUILE_LOAD_COMPILED_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/guile/3.0/site-ccache:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/guile/site/3.0" "GUILE_LOAD_COMPILED_PATH")

;;; (variable "INFOPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/info" "INFOPATH")

;;; (variable "TERM=screen.xterm-256color" "TERM")

;;; (variable "CPLUS_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include/c++:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "CPLUS_INCLUDE_PATH")

;;; (variable "ACLOCAL_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/share/aclocal" "ACLOCAL_PATH")

;;; (variable "USER=marusich" "USER")

;;; (variable "LIBRARY_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib" "LIBRARY_PATH")

;;; (variable "SHLVL=1" "SHLVL")

;;; (variable "GUIX_LOCPATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/lib/locale" "GUIX_LOCPATH")

;;; (variable "GUIX_ENVIRONMENT=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile" "GUIX_ENVIRONMENT")

;;; (variable "PS1=" "PS1")

;;; (variable "PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin:/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/sbin" "PATH")

;;; (variable "C_INCLUDE_PATH=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/include" "C_INCLUDE_PATH")

;;; (variable "_=/gnu/store/hvcq6yjfjjc7060pq09zm1rj02mivg4h-profile/bin/env" "_")
guix shell: All is good!  The shell gets correct environment variables.
[0] [env] marusich@suzaku:~/guix-master
$ 
--8<---------------cut here---------------end--------------->8---

As you can see, it seems to be working correctly here.

Here's a version of the patch that is ready for committing, with the
debug statements removed and comments added:


[-- Attachment #1.2: [PATCH] environment: Prevent PS1 from clobbering output in 'check'. --]
[-- Type: text/x-patch, Size: 3197 bytes --]

From c3eea81846ae71a246e6b592be74062f4bf26474 Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Sun, 13 Feb 2022 14:15:14 -0800
Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.

Fixes: <https://issues.guix.gnu.org/51466>.

* guix/scripts/environment.scm (child-shell-environment): In the script
executed the child shell, set PS1 to an empty value and then echo three
sentinel lines to try to "flush" the original PS1 value before printing the
environment variables.  In the parent process, read and discard all lines up
to and including the last sentinel line.  After that, read the remaining lines
as usual.
---
 guix/scripts/environment.scm | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index ec071402f4..0b137467f9 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2014, 2015, 2018 David Thompson <davet@gnu.org>
 ;;; Copyright © 2015-2022 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2018 Mike Gerwitz <mtg@gnu.org>
+;;; Copyright © 2022 Chris Marusich <cmmarusich@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -420,7 +421,16 @@ by running 'set' in the shell."
     ;; Script to obtain the list of environment variable values.  On a POSIX
     ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
     ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    ;;
+    ;; Why print "GUIX_FLUSH" a few times?  We are trying to "flush" the
+    ;; original PS1 value to the port so we can read it (and discard it)
+    ;; before we start reading the environment variables from the port.  If we
+    ;; don't do this, the original PS1 value can sometimes get interleaved
+    ;; into the output, which interferes with our parsing logic.  It's a hack,
+    ;; but in practice it seems to do the job.  If you know of a more graceful
+    ;; solution, please implement it!  See: https://issues.guix.gnu.org/51466
+    "PS1=; for i in 1 2 3; do echo GUIX_FLUSH_$i; done; \
+env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
 
   (define lines
     (match (primitive-fork)
@@ -439,6 +449,12 @@ by running 'set' in the shell."
        (let* ((port   (fdopen controller "r+l"))
               (result (begin
                         (display script port)
+                        ;; Ignore all lines up to and including the final
+                        ;; "GUIX_FLUSH" line.
+                        (while (not (string=? "GUIX_FLUSH_3\r"
+                                              (read-line port))))
+                        ;; Now (hopefully) the original PS1 value will not be
+                        ;; interleaved in the remaining lines.
                         (let loop ((lines '()))
                           (match (read-line port)
                             ((? eof-object?) (reverse lines))

base-commit: d65979c46c99dc36324ca94aa9650b9de37f22de
-- 
2.26.3


[-- Attachment #1.3: Type: text/plain, Size: 556 bytes --]


And here's its output:

--8<---------------cut here---------------start------------->8---
[0] [env] marusich@suzaku:~/guix-master
$ ./pre-inst-env guix shell --check --pure --development guix
guix shell: checking the environment variables visible from shell '/bin/bash'...
guix shell: All is good!  The shell gets correct environment variables.
[0] [env] marusich@suzaku:~/guix-master
$ 
--8<---------------cut here---------------end--------------->8---

WDYT?

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

Thanks for debugging this!

Chris Marusich <cmmarusich@gmail.com> skribis:

> From c3eea81846ae71a246e6b592be74062f4bf26474 Mon Sep 17 00:00:00 2001
> From: Chris Marusich <cmmarusich@gmail.com>
> Date: Sun, 13 Feb 2022 14:15:14 -0800
> Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.
>
> Fixes: <https://issues.guix.gnu.org/51466>.
>
> * guix/scripts/environment.scm (child-shell-environment): In the script
> executed the child shell, set PS1 to an empty value and then echo three
> sentinel lines to try to "flush" the original PS1 value before printing the
> environment variables.  In the parent process, read and discard all lines up
> to and including the last sentinel line.  After that, read the remaining lines
> as usual.

[...]

> +    ;; Why print "GUIX_FLUSH" a few times?  We are trying to "flush" the
> +    ;; original PS1 value to the port so we can read it (and discard it)
> +    ;; before we start reading the environment variables from the port.  If we
> +    ;; don't do this, the original PS1 value can sometimes get interleaved
> +    ;; into the output, which interferes with our parsing logic.  It's a hack,
> +    ;; but in practice it seems to do the job.  If you know of a more graceful
> +    ;; solution, please implement it!  See: https://issues.guix.gnu.org/51466
> +    "PS1=; for i in 1 2 3; do echo GUIX_FLUSH_$i; done; \
> +env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")

So you confirm that a single “echo” is not enough, right?

Perhaps we should unroll the ‘for’ loop for portability, to be on the
safe side.  Initially I tested with Bash, Zsh, and Fish:

  https://issues.guix.gnu.org/51285#0-lineno49

I think Fish has a very non-POSIX syntax, hence the suggestion to avoid
‘for’.

I realized that setting PS1 could interfere with the logic below that
checks for PS1.  And since it doesn’t seem to help, perhaps we can
remove “PS1=;”?

Thoughts?

Sorry to answer with yet more questions!

Thanks,
Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

Did you have a chance to look into it?

  https://issues.guix.gnu.org/53355

TIA.  :-)

Ludo’.

Ludovic Courtès <ludo@gnu.org> skribis:

> Hi Chris,
>
> Thanks for debugging this!
>
> Chris Marusich <cmmarusich@gmail.com> skribis:
>
>> From c3eea81846ae71a246e6b592be74062f4bf26474 Mon Sep 17 00:00:00 2001
>> From: Chris Marusich <cmmarusich@gmail.com>
>> Date: Sun, 13 Feb 2022 14:15:14 -0800
>> Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.
>>
>> Fixes: <https://issues.guix.gnu.org/51466>.
>>
>> * guix/scripts/environment.scm (child-shell-environment): In the script
>> executed the child shell, set PS1 to an empty value and then echo three
>> sentinel lines to try to "flush" the original PS1 value before printing the
>> environment variables.  In the parent process, read and discard all lines up
>> to and including the last sentinel line.  After that, read the remaining lines
>> as usual.
>
> [...]
>
>> +    ;; Why print "GUIX_FLUSH" a few times?  We are trying to "flush" the
>> +    ;; original PS1 value to the port so we can read it (and discard it)
>> +    ;; before we start reading the environment variables from the port.  If we
>> +    ;; don't do this, the original PS1 value can sometimes get interleaved
>> +    ;; into the output, which interferes with our parsing logic.  It's a hack,
>> +    ;; but in practice it seems to do the job.  If you know of a more graceful
>> +    ;; solution, please implement it!  See: https://issues.guix.gnu.org/51466
>> +    "PS1=; for i in 1 2 3; do echo GUIX_FLUSH_$i; done; \
>> +env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
>
> So you confirm that a single “echo” is not enough, right?
>
> Perhaps we should unroll the ‘for’ loop for portability, to be on the
> safe side.  Initially I tested with Bash, Zsh, and Fish:
>
>   https://issues.guix.gnu.org/51285#0-lineno49
>
> I think Fish has a very non-POSIX syntax, hence the suggestion to avoid
> ‘for’.
>
> I realized that setting PS1 could interfere with the logic below that
> checks for PS1.  And since it doesn’t seem to help, perhaps we can
> remove “PS1=;”?
>
> Thoughts?
>
> Sorry to answer with yet more questions!
>
> Thanks,
> Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

A friendly ping.  :-)

Ludo’.

Ludovic Courtès <ludo@gnu.org> skribis:

> Hi Chris,
>
> Did you have a chance to look into it?
>
>   https://issues.guix.gnu.org/53355
>
> TIA.  :-)
>
> Ludo’.
>
> Ludovic Courtès <ludo@gnu.org> skribis:
>
>> Hi Chris,
>>
>> Thanks for debugging this!
>>
>> Chris Marusich <cmmarusich@gmail.com> skribis:
>>
>>> From c3eea81846ae71a246e6b592be74062f4bf26474 Mon Sep 17 00:00:00 2001
>>> From: Chris Marusich <cmmarusich@gmail.com>
>>> Date: Sun, 13 Feb 2022 14:15:14 -0800
>>> Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.
>>>
>>> Fixes: <https://issues.guix.gnu.org/51466>.
>>>
>>> * guix/scripts/environment.scm (child-shell-environment): In the script
>>> executed the child shell, set PS1 to an empty value and then echo three
>>> sentinel lines to try to "flush" the original PS1 value before printing the
>>> environment variables.  In the parent process, read and discard all lines up
>>> to and including the last sentinel line.  After that, read the remaining lines
>>> as usual.
>>
>> [...]
>>
>>> +    ;; Why print "GUIX_FLUSH" a few times?  We are trying to "flush" the
>>> +    ;; original PS1 value to the port so we can read it (and discard it)
>>> +    ;; before we start reading the environment variables from the port.  If we
>>> +    ;; don't do this, the original PS1 value can sometimes get interleaved
>>> +    ;; into the output, which interferes with our parsing logic.  It's a hack,
>>> +    ;; but in practice it seems to do the job.  If you know of a more graceful
>>> +    ;; solution, please implement it!  See: https://issues.guix.gnu.org/51466
>>> +    "PS1=; for i in 1 2 3; do echo GUIX_FLUSH_$i; done; \
>>> +env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
>>
>> So you confirm that a single “echo” is not enough, right?
>>
>> Perhaps we should unroll the ‘for’ loop for portability, to be on the
>> safe side.  Initially I tested with Bash, Zsh, and Fish:
>>
>>   https://issues.guix.gnu.org/51285#0-lineno49
>>
>> I think Fish has a very non-POSIX syntax, hence the suggestion to avoid
>> ‘for’.
>>
>> I realized that setting PS1 could interfere with the logic below that
>> checks for PS1.  And since it doesn’t seem to help, perhaps we can
>> remove “PS1=;”?
>>
>> Thoughts?
>>
>> Sorry to answer with yet more questions!
>>
>> Thanks,
>> Ludo’.

bug#53355: guix shell --check: confusing error message

[Chris Marusich]

[-- Attachment #1.1: Type: text/plain, Size: 2324 bytes --]

Hi Ludo,

Ludovic Courtès <ludo@gnu.org> writes:

> So you confirm that a single “echo” is not enough, right?

I didn't test one specifically. It might work with just one, but it did
work with three.  If we want to proceed with the "echo" approach, let me
know and I'll test just one echo to see if that is reliable enough.

> Perhaps we should unroll the ‘for’ loop for portability, to be on the
> safe side.  Initially I tested with Bash, Zsh, and Fish:
>
>   https://issues.guix.gnu.org/51285#0-lineno49
>
> I think Fish has a very non-POSIX syntax, hence the suggestion to avoid
> ‘for’.

I see.  Yes, I'll do that if we decide to go with the echo-based
approach.

> I realized that setting PS1 could interfere with the logic below that
> checks for PS1.  And since it doesn’t seem to help, perhaps we can
> remove “PS1=;”?

I recall that I tried removing PS1, and I still had trouble.  I believe
it was because even if we unset PS1 as the very first command we do, the
original prompt is still printed.  Foreign distros usually set PS1 to
something, and whatever that is will be printed before we have a chance
to input any commands.  It's hard to avoid that in general.

> Thoughts?

One alternative method I tried successfully in a variety of shells was
to use shell redirection (see attached).  I like this approach.
However, this will only work in shells that support redirection.  I
recall testing with bash, ash (busybox's shell), dash, zsh, fish, ksh,
and csh.  I recall that only csh failed, since it doesn't support
redirection.

I personally like the attached patch better than what I proposed
earlier.  The earlier patch just echoes a few times.  Presumably, it
only works because the PS1 prompt is likely (but not guaranteed) to be
emitted before the last of the echo commands finishes printing.  I'd
rather just control the desired output and ignore PS1 entirely, and that
is what the attached patch accomplishes using FDs.  However, if support
for shells without redirection is a requirement, then maybe the original
hack (echo a few times) is OK, or perhaps we need something else.

How would you like to proceed?  Is it OK to rely on shell redirection?

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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From 9a1cef589abf01b61e22656f44c76441f4c50ffd Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Fri, 11 Mar 2022 00:20:12 -0800
Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.

Fixes: <https://issues.guix.gnu.org/51466>.

* guix/scripts/environment.scm (child-shell-environment) [shell-pipe]
[shell-pipe-in, shell-pipe-out]: New local variables.
[script]: Redirect the stdout of each command to the file descriptor of the
shell-pipe-out port.
[lines]: In the child, close shell-pipe-in before starting the shell.  In the
parent, close shell-pipe-out before sending the script to the shell.  Read
lines from shell-pipe-in, not port, so that the shell's PS1 prompt cannot
clobber the lines.  Close shell-pipe-in just before waiting on the child.
---
 guix/scripts/environment.scm | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 3216235937..f0cb341aab 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -48,6 +48,7 @@ (define-module (guix scripts environment)
   #:autoload   (gnu packages bash) (bash)
   #:autoload   (gnu packages bootstrap) (bootstrap-executable %bootstrap-guile)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 format)
   #:autoload   (ice-9 rdelim) (read-line)
   #:use-module (ice-9 vlist)
   #:use-module (srfi srfi-1)
@@ -418,11 +419,23 @@ (define (child-shell-environment shell profile manifest)
   (define-values (controller inferior)
     (openpty))
 
+  (define shell-pipe (pipe))
+  (define shell-pipe-in (car shell-pipe))
+  (define shell-pipe-out (cdr shell-pipe))
+
   (define script
-    ;; Script to obtain the list of environment variable values.  On a POSIX
-    ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
-    ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    ;; Script to obtain the list of environment variable values.
+    ;;
+    ;; On a POSIX shell we can rely on 'set', but on fish we have to use 'env'
+    ;; (fish's 'set' truncates values and prints them in a different format).
+    ;;
+    ;; Unless we redirect output to a dedicated file descriptor, there is a
+    ;; risk that the shell's PS1 prompt might clobber the output.  See:
+    ;; https://issues.guix.gnu.org/53355
+    (let ((out-fd (port->fdes shell-pipe-out)))
+      (format
+       #f "env 1>&~d || /usr/bin/env 1>&~d || set 1>&~d; \
+echo GUIX-CHECK-DONE 1>&~d; read x; exit\n" out-fd out-fd out-fd out-fd)))
 
   (define lines
     (match (primitive-fork)
@@ -432,17 +445,22 @@ (define lines
            (load-profile profile manifest #:pure? #t)
            (setenv "GUIX_ENVIRONMENT" profile)
            (close-fdes controller)
+           (close-port shell-pipe-in)
            (login-tty inferior)
            (execl shell shell))
          (lambda _
            (primitive-exit 127))))
       (pid
        (close-fdes inferior)
+       (close-port shell-pipe-out)
        (let* ((port   (fdopen controller "r+l"))
               (result (begin
                         (display script port)
                         (let loop ((lines '()))
-                          (match (read-line port)
+                          ;; Read from our special port, not from the
+                          ;; controller port, to prevent the shell's PS1
+                          ;; prompt from getting mixed into what we read.
+                          (match (read-line shell-pipe-in)
                             ((? eof-object?) (reverse lines))
                             ("GUIX-CHECK-DONE\r"
                              (display "done\n" port)
@@ -452,6 +470,7 @@ (define lines
                              (loop (cons (string-drop-right line 1)
                                          lines))))))))
          (close-port port)
+         (close-port shell-pipe-in)
          (waitpid pid)
          result))))
 

base-commit: adf5ae5a412ed13302186dd4ce8e2df783d4515d
-- 
2.34.0


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bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> One alternative method I tried successfully in a variety of shells was
> to use shell redirection (see attached).  I like this approach.
> However, this will only work in shells that support redirection.  I
> recall testing with bash, ash (busybox's shell), dash, zsh, fish, ksh,
> and csh.  I recall that only csh failed, since it doesn't support
> redirection.

That’s a good success list in my view; not being a POSIX shell, (t)csh
was already excluded from the list in the original submission I think:
<https://issues.guix.gnu.org/51285>.

> I personally like the attached patch better than what I proposed
> earlier.  The earlier patch just echoes a few times.  Presumably, it
> only works because the PS1 prompt is likely (but not guaranteed) to be
> emitted before the last of the echo commands finishes printing.  I'd
> rather just control the desired output and ignore PS1 entirely, and that
> is what the attached patch accomplishes using FDs.  However, if support
> for shells without redirection is a requirement, then maybe the original
> hack (echo a few times) is OK, or perhaps we need something else.
>
> How would you like to proceed?  Is it OK to rely on shell redirection?

Yeah, I think so.  This new approach looks more robust.

> From 9a1cef589abf01b61e22656f44c76441f4c50ffd Mon Sep 17 00:00:00 2001
> From: Chris Marusich <cmmarusich@gmail.com>
> Date: Fri, 11 Mar 2022 00:20:12 -0800
> Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.
>
> Fixes: <https://issues.guix.gnu.org/51466>.
>
> * guix/scripts/environment.scm (child-shell-environment) [shell-pipe]
> [shell-pipe-in, shell-pipe-out]: New local variables.
> [script]: Redirect the stdout of each command to the file descriptor of the
> shell-pipe-out port.
> [lines]: In the child, close shell-pipe-in before starting the shell.  In the
> parent, close shell-pipe-out before sending the script to the shell.  Read
> lines from shell-pipe-in, not port, so that the shell's PS1 prompt cannot
> clobber the lines.  Close shell-pipe-in just before waiting on the child.

LGTM, please push!

Ludo’.

bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi Ludo,

Thank you for the review!

Ludovic Courtès <ludo@gnu.org> writes:

> LGTM, please push!

Before pushing, I did some more tests to make sure it was still working.
When I did this, I noticed that read-line was no longer returning
strings that end in "\r".  This prevents child-shell-environment from
behaving correctly, since it incorrectly assumes that all the lines end
in "\r", stripping it off unconditionally.  In the past, I'm sure
read-line was returning strings that end in "\r".  I don't know what
changed, but I've attached a second patch that fixes this issue, also.

Unless you have more feedback, I'll go ahead and push both patches to
master in a few days.

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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From c4fee9e63f8cb694de86ae46bd1e2e4c692eb6f6 Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Sun, 19 Jun 2022 13:16:04 -0700
Subject: [PATCH] environment: Don't assume that lines have a trailing "\r".

I've noticed that the child-shell-environment procedure is misbehaving on my
computer because the lines returned by read-line do not have a trailing "\r".
In the past, I recall that such lines did in fact have a trailing "\r".  I'm
not sure why it changed, but it seems prudent to just rewrite this code to
tolerate both cases, since it seems that both cases can happen.

* guix/scripts/environment.scm (child-shell-environment) [lines]: Instead of
checking if the line exactly matches "GUIX_CHECK_DONE\r"; check if the line
begins with "GUIX_CHECK_DONE".  Instead of always stripping the trailing
character from the line, only do it if the line has a trailing "\r".
---
 guix/scripts/environment.scm | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index f0cb341aab..1fb4f5b7c6 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -462,13 +462,18 @@ (define lines
                           ;; prompt from getting mixed into what we read.
                           (match (read-line shell-pipe-in)
                             ((? eof-object?) (reverse lines))
-                            ("GUIX-CHECK-DONE\r"
+                            ((? (lambda (line)
+                                  ;; The line might or might not have a trailing \r.
+                                  (string-prefix? "GUIX-CHECK-DONE" line)))
                              (display "done\n" port)
                              (reverse lines))
                             (line
-                             ;; Drop the '\r' from LINE.
-                             (loop (cons (string-drop-right line 1)
-                                         lines))))))))
+                             ;; Strip the trailing '\r' from LINE if present.
+                             (let ((stripped-line
+                                    (if (string-suffix? "\r" line)
+                                        (string-drop-right line 1)
+                                        line)))
+                               (loop (cons stripped-line lines)))))))))
          (close-port port)
          (close-port shell-pipe-in)
          (waitpid pid)
-- 
2.34.0


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bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi,

Chris Marusich <cmmarusich@gmail.com> skribis:

> Before pushing, I did some more tests to make sure it was still working.
> When I did this, I noticed that read-line was no longer returning
> strings that end in "\r".  This prevents child-shell-environment from
> behaving correctly, since it incorrectly assumes that all the lines end
> in "\r", stripping it off unconditionally.  In the past, I'm sure
> read-line was returning strings that end in "\r".  I don't know what
> changed, but I've attached a second patch that fixes this issue, also.

Weird, not sure what could have changed.

> Unless you have more feedback, I'll go ahead and push both patches to
> master in a few days.

Great, thank you!

Ludo’.

bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[bokr]

Hi Chris,

Did you observe this behaviour inside a git repo directory?
I wonder if this git security thing could be relevant:
    https://lwn.net/Articles/892755/
It makes also me wonder about readline completion stuff
possibly interacting. Isn't that implemented with readline?

I have had some mystery bash parsing errors, and I noticed
    set|less
shows a heck of a lot of functions defined that I don't
remember seeing in the past. 
Anyway, shouldn't stuff like that have better hygiene than just prefixed
_underscore ? Or maybe set|less doesn't show all that on your system?

Disclaimer: I played a lot of games trying to make stuff conditional
at login, where I  renamed .bash_profile and .bashrc (e.g. .my_bashrc)
which brought .profile into play, and I messed with the downstream
of that to source some .my_'s conditionally, so I've go a fragile mess right now ;/

Anyway, did you determine why things changed in the first place?
Or will this be a whack-a-mole game with future weirdnesses? :)

Semms like IWBN to have interfaces governed by contracts :)

Best,
Bengt Richter

On +2022-06-19 13:40:50 -0700, Chris Marusich wrote:
> Hi Ludo,
> 
> Thank you for the review!
> 
> Ludovic Courtès <ludo@gnu.org> writes:
> 
> > LGTM, please push!
> 
> Before pushing, I did some more tests to make sure it was still working.
> When I did this, I noticed that read-line was no longer returning
> strings that end in "\r".  This prevents child-shell-environment from
> behaving correctly, since it incorrectly assumes that all the lines end
> in "\r", stripping it off unconditionally.  In the past, I'm sure
> read-line was returning strings that end in "\r".  I don't know what
> changed, but I've attached a second patch that fixes this issue, also.
> 
> Unless you have more feedback, I'll go ahead and push both patches to
> master in a few days.
> 
> -- 
> Chris
> 
> PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

> From c4fee9e63f8cb694de86ae46bd1e2e4c692eb6f6 Mon Sep 17 00:00:00 2001
> From: Chris Marusich <cmmarusich@gmail.com>
> Date: Sun, 19 Jun 2022 13:16:04 -0700
> Subject: [PATCH] environment: Don't assume that lines have a trailing "\r".
> 
> I've noticed that the child-shell-environment procedure is misbehaving on my
> computer because the lines returned by read-line do not have a trailing "\r".
> In the past, I recall that such lines did in fact have a trailing "\r".  I'm
> not sure why it changed, but it seems prudent to just rewrite this code to
> tolerate both cases, since it seems that both cases can happen.
> 
> * guix/scripts/environment.scm (child-shell-environment) [lines]: Instead of
> checking if the line exactly matches "GUIX_CHECK_DONE\r"; check if the line
> begins with "GUIX_CHECK_DONE".  Instead of always stripping the trailing
> character from the line, only do it if the line has a trailing "\r".
> ---
>  guix/scripts/environment.scm | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
> index f0cb341aab..1fb4f5b7c6 100644
> --- a/guix/scripts/environment.scm
> +++ b/guix/scripts/environment.scm
> @@ -462,13 +462,18 @@ (define lines
>                            ;; prompt from getting mixed into what we read.
>                            (match (read-line shell-pipe-in)
>                              ((? eof-object?) (reverse lines))
> -                            ("GUIX-CHECK-DONE\r"
> +                            ((? (lambda (line)
> +                                  ;; The line might or might not have a trailing \r.
> +                                  (string-prefix? "GUIX-CHECK-DONE" line)))
>                               (display "done\n" port)
>                               (reverse lines))
>                              (line
> -                             ;; Drop the '\r' from LINE.
> -                             (loop (cons (string-drop-right line 1)
> -                                         lines))))))))
> +                             ;; Strip the trailing '\r' from LINE if present.
> +                             (let ((stripped-line
> +                                    (if (string-suffix? "\r" line)
> +                                        (string-drop-right line 1)
> +                                        line)))
> +                               (loop (cons stripped-line lines)))))))))
>           (close-port port)
>           (close-port shell-pipe-in)
>           (waitpid pid)
> -- 
> 2.34.0
> 

bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Bengt Richter]

Sorry to reply to myself, but forgot to illustrate.

On +2022-06-20 12:12:10 +0200, bokr@bokr.com wrote:
> Hi Chris,
[...]
> 
> I have had some mystery bash parsing errors, and I noticed
>     set|less
> shows a heck of a lot of functions defined that I don't
> remember seeing in the past. 
> Anyway, shouldn't stuff like that have better hygiene than just prefixed
> _underscore ? Or maybe set|less doesn't show all that on your system?
>

There are a couple functions without prefixed underscore too,
which invoke some underscore-prefixed ones that look too trusting
of their arguments if you ask me: can someone declare these safe?

    I think I can grok quote () ...
(escape single quotes and enclose result in single quotes, trusting bash state)
But what if I want to define my own function quote?? How would I know I was
overriding this? I really don't like my programming space occupied by unknowns :-(

--8<---------------cut here---------------start------------->8---
quote () 
{ 
    local quoted=${1//\'/\'\\\'\'};
    printf "'%s'" "$quoted"
}
--8<---------------cut here---------------end--------------->8---

    but this one below will take more time than I want to spend on code
I'm not intentionally going to use, and which invites name clashes
in my command name space :-(

--8<---------------cut here---------------start------------->8---
quote_readline () 
{ 
    local quoted;
    _quote_readline_by_ref "$1" ret;
    printf %s "$ret"
}
--8<---------------cut here---------------end--------------->8---

    where the above calls this:

--8<---------------cut here---------------start------------->8---
_quote_readline_by_ref () 
{ 
    if [ -z "$1" ]; then
        printf -v $2 %s "$1";
    else
        if [[ $1 == \'* ]]; then
            printf -v $2 %s "${1:1}";
        else
            if [[ $1 == ~* ]]; then
                printf -v $2 ~%q "${1:1}";
            else
                printf -v $2 %q "$1";
            fi;
        fi;
    fi;
    [[ ${!2} == \$* ]] && eval $2=${!2}
}
--8<---------------cut here---------------end--------------->8---

HTH somehow.
--
Regards,
Bengt Richter

bug#51466: bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Bengt Richter]

Sorry again, but I found the source:

tl;dr: These functions are defined in
    /usr/share/bash-completion/bash_completion
which looks awful kludgey to me, (however clever :)

There is a reference to
    http://lists.gnu.org/archive/html/bug-bash/2009-03/msg00155.html
in the header comments for
    _quote_readline_by_ref () 

I also found
    https://askubuntu.com/questions/571544/bash-tab-completion-bash-unexpected-eof-while-looking-for-matching-bash
My bet is there is at least one bug active now.

Completion is really nice when it works, but IMO they certainly
shouldn't use a name like unadorned ``quote'' in their implementation.

And I think it would be prettier in scheme :)
Lots could be prettier if bash could be extended with scheme.

I'm about out of time to chase this, but I expect to bump into it again ;/
HTH.
--
Regards,
Bengt Richter

On +2022-06-20 19:56:56 +0200, Bengt Richter wrote:
> Sorry to reply to myself, but forgot to illustrate.
> 
> On +2022-06-20 12:12:10 +0200, bokr@bokr.com wrote:
> > Hi Chris,
> [...]
> > 
> > I have had some mystery bash parsing errors, and I noticed
> >     set|less
> > shows a heck of a lot of functions defined that I don't
> > remember seeing in the past. 
> > Anyway, shouldn't stuff like that have better hygiene than just prefixed
> > _underscore ? Or maybe set|less doesn't show all that on your system?
> >
> 
> There are a couple functions without prefixed underscore too,
> which invoke some underscore-prefixed ones that look too trusting
> of their arguments if you ask me: can someone declare these safe?
> 
>     I think I can grok quote () ...
> (escape single quotes and enclose result in single quotes, trusting bash state)
> But what if I want to define my own function quote?? How would I know I was
> overriding this? I really don't like my programming space occupied by unknowns :-(
> 
> --8<---------------cut here---------------start------------->8---
> quote () 
> { 
>     local quoted=${1//\'/\'\\\'\'};
>     printf "'%s'" "$quoted"
> }
> --8<---------------cut here---------------end--------------->8---
> 
>     but this one below will take more time than I want to spend on code
> I'm not intentionally going to use, and which invites name clashes
> in my command name space :-(
> 
> --8<---------------cut here---------------start------------->8---
> quote_readline () 
> { 
>     local quoted;
>     _quote_readline_by_ref "$1" ret;
>     printf %s "$ret"
> }
> --8<---------------cut here---------------end--------------->8---
> 
>     where the above calls this:
> 
> --8<---------------cut here---------------start------------->8---
> _quote_readline_by_ref () 
> { 
>     if [ -z "$1" ]; then
>         printf -v $2 %s "$1";
>     else
>         if [[ $1 == \'* ]]; then
>             printf -v $2 %s "${1:1}";
>         else
>             if [[ $1 == ~* ]]; then
>                 printf -v $2 ~%q "${1:1}";
>             else
>                 printf -v $2 %q "$1";
>             fi;
>         fi;
>     fi;
>     [[ ${!2} == \$* ]] && eval $2=${!2}
> }
> --8<---------------cut here---------------end--------------->8---
> 
> HTH somehow.
> --
> Regards,
> Bengt Richter
> 
> 
> 

bug#51466: bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Thiago Jung Bauermann via Bug reports for GNU Guix]

Hello,

Bengt Richter <bokr@bokr.com> writes:

> Lots could be prettier if bash could be extended with scheme.

Today is your lucky day. :-)

$ guix show guile-bash | recsel -p name,synopsis
name: guile-bash
synopsis: Extend Bash using Guile  

-- 
Thanks
Thiago

bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi Ludo & Everyone,

Chris Marusich <cmmarusich@gmail.com> writes:

> Is it OK to rely on shell redirection?

It turns out that it is probably not OK to rely on shell redirection in
this case, after all.  For example, "dash does not support multi-digit
file descriptors":

https://bugs.launchpad.net/ubuntu/+source/dash/+bug/249620

Indeed, the patch I proposed earlier to rely on shell redirection caused
a command like

./pre-inst-env env SHELL=/gnu/store/nm0hccsphymxi8c24xmg6ixm9vcf25xb-dash-0.5.11.5/bin/dash guix shell --check --container -D guix

to hang.  It hangs because the FD Guile chooses to create and embed in
the script is 19 (on my machine, at least).  A redirection like
"env >&19" causes dash to error out, so no environment information gets
sent back to the parent process.  The same issue seemed to occur for the
ksh from our oksh package.

To resolve this, I changed the code so that it just writes to a
temporary file.  This is simple and more robust.  With the attached
patch, I was able to use a command like the one above to verify that
"guix environment --check" works correctly for Guix-built bash, dash,
ksh, fish, zsh, and ash.  I also verified that it works for Fedora's
/bin/sh and /bin/bash.

What do you think of this file-based approach?  Supporting many
different shells is pretty tricky, but I think this patch does a good
enough job.

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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From ef8d12a1d44903eafca7153c9344263b1d5d7d56 Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Fri, 11 Mar 2022 00:20:12 -0800
Subject: [PATCH] environment: Prevent PS1 from clobbering output in 'check'.

Fixes: <https://issues.guix.gnu.org/51466>.

* guix/scripts/environment.scm (child-shell-environment) [temporary-file-port]
[temporary-file]: New local variables.
[script]: Redirect stdout to the temporary file.
[lines]: In the parent, send the script to the shell, wait for the shell to
exit, and then read lines from the temporary file.  Use a dynamic-wind
expression to ensure we always close port, close temporary-file-port, and
delete temporary-file.
---
 guix/scripts/environment.scm | 63 ++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 20 deletions(-)

diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 3216235937..b02b0771e3 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -48,6 +48,7 @@ (define-module (guix scripts environment)
   #:autoload   (gnu packages bash) (bash)
   #:autoload   (gnu packages bootstrap) (bootstrap-executable %bootstrap-guile)
   #:use-module (ice-9 match)
+  #:use-module (ice-9 format)
   #:autoload   (ice-9 rdelim) (read-line)
   #:use-module (ice-9 vlist)
   #:use-module (srfi srfi-1)
@@ -418,14 +419,27 @@ (define (child-shell-environment shell profile manifest)
   (define-values (controller inferior)
     (openpty))
 
+  (define temporary-file-port (mkstemp "/tmp/guix-env.XXXXXX"))
+
+  (define temporary-file (port-filename temporary-file-port))
+
   (define script
-    ;; Script to obtain the list of environment variable values.  On a POSIX
-    ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
-    ;; 'set' truncates values and prints them in a different format.)
-    "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+    ;; Script to obtain the list of environment variable values.
+    ;;
+    ;; On a POSIX shell we can rely on 'set', but on fish we have to use 'env'
+    ;; (fish's 'set' truncates values and prints them in a different format).
+    ;;
+    ;; Unless we redirect output to a file, there is a risk that the shell's
+    ;; PS1 prompt might clobber the output.  See:
+    ;; https://issues.guix.gnu.org/53355
+    (format
+     #f "env >~a || /usr/bin/env >~a || set >~a; \
+echo GUIX-CHECK-DONE >>~a; exit\n"
+     temporary-file temporary-file temporary-file temporary-file))
 
   (define lines
     (match (primitive-fork)
+      ;; Child
       (0
        (catch #t
          (lambda ()
@@ -436,24 +450,33 @@ (define lines
            (execl shell shell))
          (lambda _
            (primitive-exit 127))))
+      ;; Parent
       (pid
        (close-fdes inferior)
-       (let* ((port   (fdopen controller "r+l"))
-              (result (begin
-                        (display script port)
-                        (let loop ((lines '()))
-                          (match (read-line port)
-                            ((? eof-object?) (reverse lines))
-                            ("GUIX-CHECK-DONE\r"
-                             (display "done\n" port)
-                             (reverse lines))
-                            (line
-                             ;; Drop the '\r' from LINE.
-                             (loop (cons (string-drop-right line 1)
-                                         lines))))))))
-         (close-port port)
-         (waitpid pid)
-         result))))
+       (let* ((port   (fdopen controller "r+l")))
+         (dynamic-wind
+           (const #t)
+           (lambda ()
+             (display script port)
+             ;; Wait until the shell is done writing to the temporary file.
+             (waitpid pid)
+             (let loop ((lines '()))
+               ;; Read from the temporary file, not from the controller port, to
+               ;; prevent the shell's PS1 prompt from getting mixed into what we
+               ;; read.  See: https://issues.guix.gnu.org/51466
+               (match (read-line temporary-file-port)
+                 ((? eof-object?) (reverse lines))
+                 ("GUIX-CHECK-DONE"
+                  (reverse lines))
+                 (line
+                  (loop (cons line lines))))))
+           (lambda ()
+             (close-port temporary-file-port)
+             ;; The temporary file might not exist if something weird happens
+             ;; in the child shell that prevents it from even writing to the
+             ;; file (e.g. the shell fails to start for some reason).
+             (false-if-exception (delete-file temporary-file))
+             (close-port port)))))))
 
   (fold (lambda (line table)
           ;; Note: 'set' in fish outputs "NAME VALUE" instead of "NAME=VALUE"

base-commit: 319b8331b2357e12ec9edb9665513c32bef56622
-- 
2.34.0


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bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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Chris Marusich schreef op za 25-06-2022 om 02:07 [-0700]:
> It turns out that it is probably not OK to rely on shell redirection
> in
> this case, after all.  For example, "dash does not support multi-
> digit
> file descriptors":
> 
> https://bugs.launchpad.net/ubuntu/+source/dash/+bug/249620

I consider temporary files to be more fragile -- you have to take care
of file permissions, removing the file afterwards even after an
interrupt with C-c, deleting the temporary file can fail, there might
be an out-of-space error, in case of file system corruption things
might be remounted read-only, some other program could read, write or
delete the file ..., so I think it would be best to just fix the bug in
dash instead.

Greetings,
Maxime.

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bug#51466: bug#53355: guix shell --check: confusing error message

[Chris Marusich]

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Hi Maxime,

Maxime Devos <maximedevos@telenet.be> writes:

> Chris Marusich schreef op za 25-06-2022 om 02:07 [-0700]:
>> It turns out that it is probably not OK to rely on shell redirection
>> in
>> this case, after all.  For example, "dash does not support multi-
>> digit
>> file descriptors":
>> 
>> https://bugs.launchpad.net/ubuntu/+source/dash/+bug/249620
>
> I consider temporary files to be more fragile -- you have to take care
> of file permissions, removing the file afterwards even after an
> interrupt with C-c, deleting the temporary file can fail, there might
> be an out-of-space error, in case of file system corruption things
> might be remounted read-only, some other program could read, write or
> delete the file ..., so I think it would be best to just fix the bug in
> dash instead.

Yes, I agree those are good reasons to avoid a temporary file if we can.
To that end, do you know if we can somehow force Guile to use a specific
file descriptor for the pipe?  In the patch I wrote earlier, which uses
redirection, the problem was that I could not control Guile's choice of
file descriptors.  Guile chose file descriptor 19 for one end of the
pipe, and I don't know how to make it use anything else.  If we can
arrange for Guile to consistently use file descriptor 7, for example,
then probably it would work in all the shell I've tested.

I wonder if maybe I can just duplicate the file descriptor?  I don't
know; if for example Guile reserves all the file descriptors below 10
for other uses, it might be hard.

What do you think?  Is there a way to do it?

-- 
Chris

PGP: https://savannah.gnu.org/people/viewgpg.php?user_id=106836

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bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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Chris Marusich schreef op za 25-06-2022 om 09:52 [-0700]:
> Yes, I agree those are good reasons to avoid a temporary file if we
> can.
> To that end, do you know if we can somehow force Guile to use a
> specific
> file descriptor for the pipe?  In the patch I wrote earlier, which
> uses
> redirection, the problem was that I could not control Guile's choice
> of
> file descriptors.  Guile chose file descriptor 19 for one end of the
> pipe, and I don't know how to make it use anything else.  If we can
> arrange for Guile to consistently use file descriptor 7, for example,
> then probably it would work in all the shell I've tested.
> 
> I wonder if maybe I can just duplicate the file descriptor?  I don't
> know; if for example Guile reserves all the file descriptors below 10
> for other uses, it might be hard.
> 

Have a look at ‘(guile)Ports and File Descriptors’.  It has lots of
procedures for duplicating and renumbering.  That's fragile though, you
might accidentally overwrite an fd that's being used for something
else.

(Normally move->fdes would prevent overwriting things by moving pre-
existing fds out of the way, adjusting ports automatically, but move-
>fdes doesn't know (yet) about the pipe that Guile uses for
finalisation, see maybe:
<https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48563>)

I think it would be best to patch the dash appropriately (though fixing
move->fdes would be nice too).

Greetings,
Maximee.

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bug#51466: bug#53355: guix shell --check: confusing error message

[bokr]

On +2022-06-25 19:40:48 +0200, Maxime Devos wrote:
> Chris Marusich schreef op za 25-06-2022 om 09:52 [-0700]:
> > Yes, I agree those are good reasons to avoid a temporary file if we
> > can.
> > To that end, do you know if we can somehow force Guile to use a
> > specific
> > file descriptor for the pipe?  In the patch I wrote earlier, which
> > uses
> > redirection, the problem was that I could not control Guile's choice
> > of
> > file descriptors.  Guile chose file descriptor 19 for one end of the
> > pipe, and I don't know how to make it use anything else.  If we can
> > arrange for Guile to consistently use file descriptor 7, for example,
> > then probably it would work in all the shell I've tested.
> > 
> > I wonder if maybe I can just duplicate the file descriptor?  I don't
> > know; if for example Guile reserves all the file descriptors below 10
> > for other uses, it might be hard.
> > 
> 
> Have a look at ‘(guile)Ports and File Descriptors’.  It has lots of
> procedures for duplicating and renumbering.  That's fragile though, you
> might accidentally overwrite an fd that's being used for something
> else.
> 
> (Normally move->fdes would prevent overwriting things by moving pre-
> existing fds out of the way, adjusting ports automatically, but move-
> >fdes doesn't know (yet) about the pipe that Guile uses for
> finalisation, see maybe:
> <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48563>)
> 
> I think it would be best to patch the dash appropriately (though fixing
> move->fdes would be nice too).
> 
> Greetings,
> Maximee.

Could this help?:

(from man 2 openat (scroll down a fair bit):
-8<---------------cut here---------------start------------->8---
  There are two main use cases for O_TMPFILE:

  *  Improved tmpfile(3) functionality: race-free creation of temporary files that (1) are automatically
     deleted  when closed; (2) can never be reached via any pathname; (3) are not subject to symlink at‐
     tacks; and (4) do not require the caller to devise unique names.

  *  Creating a file that is initially invisible, which is then populated with data and adjusted to have
     appropriate  filesystem  attributes (fchown(2), fchmod(2), fsetxattr(2), etc.)  before being atomi‐
     cally linked into the filesystem in a fully formed state (using linkat(2) as described above).

  O_TMPFILE requires support by the underlying filesystem; only a subset of  Linux  filesystems  provide
  that  support.   In  the  initial  implementation,  support was provided in the ext2, ext3, ext4, UDF,
  Minix, and shmem filesystems.  Support for other filesystems has subsequently been added  as  follows:
  XFS (Linux 3.15); Btrfs (Linux 3.16); F2FS (Linux 3.16); and ubifs (Linux 4.9)
--8<---------------cut here---------------end--------------->8---

BTW, IIRC, this can be used to create an invisible file that
can be mmap-ed, and the mmap will persist when you delete
the file. Which then can be used as an anonymous buffer
passed to wayland, along with metadate saying what the buffer
contains, e.g. different kinds of rgb or rgba permutations
and encodings, (or anything, which you can tell wayland just
to keep track of for you.

You need a directory for openat, so probably
    XDG_RUNTIME_DIR=/run/user/1000
is suitable if it exists. Worked in my case.

HTH
--
Regards,
Bengt Richter

bug#51466: bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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bokr@bokr.com schreef op za 25-06-2022 om 22:06 [+0200]:
> BTW, IIRC, this can be used to create an invisible file that

Invisible files don't have file names, so they cannot be put in the
tiny shell script:

> +    (format
> +     #f "env >~a || /usr/bin/env >~a || set >~a; \
> +echo GUIX-CHECK-DONE >>~a; exit\n"
> +     temporary-file temporary-file temporary-file temporary-file))

Also, I just noticed that this tiny shell script isn't quoting
anything, so you'll get in trouble if $TMPDIR (or was it $TEMPDIR,
whatever) contains " or ' or \ or whatever.

So to avoid messy and fragile escaping, I'd recommend to work with file
descriptors.

Greetings,
Maxime.

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bug#51466: bug#53355: guix shell --check: confusing error message

[Josselin Poiret via Bug reports for GNU Guix]

Hello everyone, 

Maxime Devos <maximedevos@telenet.be> writes:

> Chris Marusich schreef op za 25-06-2022 om 09:52 [-0700]:
>> [...]
>> the problem was that I could not control Guile's choice
>> of
>> file descriptors.  Guile chose file descriptor 19 for one end of the
>> pipe, and I don't know how to make it use anything else.  If we can
>> arrange for Guile to consistently use file descriptor 7, for example,
>> then probably it would work in all the shell I've tested.
> Have a look at ‘(guile)Ports and File Descriptors’.  It has lots of
> procedures for duplicating and renumbering.  That's fragile though, you
> might accidentally overwrite an fd that's being used for something
> else.

Just my 2¢, from my experience, Guile uses a lot of fds (`guile -q` uses
15).  I'm not sure it would be safe or advisable to move fds, since we
cannot be sure that they're backing ports or not, and if they're not it
would break things.  In general, the Guile ports/fds interface works ok,
but there is a lot of code that is fragile and doesn't handle
edge-cases.

Best,
-- 
Josselin Poiret

bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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Josselin Poiret schreef op zo 26-06-2022 om 12:33 [+0200]:
> Just my 2¢, from my experience, Guile uses a lot of fds (`guile -q` uses
> 15).  I'm not sure it would be safe or advisable to move fds, since we
> cannot be sure that they're backing ports or not, and if they're not it
> would break things

As mentioned previously, move->fdes looks in the port table to see if
the file descriptor things are being moved too is still in use, and if
so, moves that (fd, port) out of the way first, so should be safe.

That only works if Guile knows about the fd though, and Guile currently
does not know about it's own finalisation pipe, which I think is the
cause of <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48563>, so
currently still fragile ...

(To be clear, I still recommend just fixing dash ...)

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bug#53355: guix shell --check: confusing error message

[Tobias Geerinckx-Rice via Bug reports for GNU Guix]

On 26 June 2022 13:07:11 UTC, Maxime Devos <maximedevos@telenet.be> wrote:
>(To be clear, I still recommend just fixing dash ...)

That's the long-term solution, but Guix needs a work-around regardless.


Kind regards,

T G-R

Sent on the go.  Excuse or enjoy my brevity.

bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi Chris,

Chris Marusich <cmmarusich@gmail.com> skribis:

> It turns out that it is probably not OK to rely on shell redirection in
> this case, after all.  For example, "dash does not support multi-digit
> file descriptors":
>
> https://bugs.launchpad.net/ubuntu/+source/dash/+bug/249620

Bah.  :-/

[...]

> To resolve this, I changed the code so that it just writes to a
> temporary file.  This is simple and more robust.  With the attached
> patch, I was able to use a command like the one above to verify that
> "guix environment --check" works correctly for Guix-built bash, dash,
> ksh, fish, zsh, and ash.  I also verified that it works for Fedora's
> /bin/sh and /bin/bash.
>
> What do you think of this file-based approach?  Supporting many
> different shells is pretty tricky, but I think this patch does a good
> enough job.

Like Maxime, I’d rather not create a temporary file.

I agree that Dash should be fixed, but in the meantime, we still want
our stuff to work with the broken Dash (it’s the default on
Debian/Ubuntu, isn’t it?).

I don’t have a better idea to offer though…

Ludo’.

bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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Ludovic Courtès schreef op ma 27-06-2022 om 12:17 [+0200]:
> I agree that Dash should be fixed, but in the meantime, we still want
> our stuff to work with the broken Dash (it’s the default on
> Debian/Ubuntu, isn’t it?).

If Dash is fixed, then it's non-broken, and we don't have to work with
the broken Dash.  I don't expect fixing it to be more complicated than
the work-arounds in Guile.

> On 26 June 2022 13:07:11 UTC, Maxime Devos <maximedevos@telenet.be>
> wrote:
> >(To be clear, I still recommend just fixing dash ...)
> 
> That's the long-term solution, but Guix needs a work-around
> regardless.

Fixing dash seems to me something that could be done in the short term?

Greetings,
Maxime

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bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Maxime Devos <maximedevos@telenet.be> skribis:

> Ludovic Courtès schreef op ma 27-06-2022 om 12:17 [+0200]:
>> I agree that Dash should be fixed, but in the meantime, we still want
>> our stuff to work with the broken Dash (it’s the default on
>> Debian/Ubuntu, isn’t it?).
>
> If Dash is fixed, then it's non-broken

Even if a fix goes upstream today, people will still be using a distro
with the broken Dash for years, literally.  That’s why I think we have
to cope with it.

Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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Ludovic Courtès schreef op di 28-06-2022 om 09:45 [+0200]:
> Maxime Devos <maximedevos@telenet.be> skribis:
> 
> > Ludovic Courtès schreef op ma 27-06-2022 om 12:17 [+0200]:
> > > I agree that Dash should be fixed, but in the meantime, we still want
> > > our stuff to work with the broken Dash (it’s the default on
> > > Debian/Ubuntu, isn’t it?).
> > 
> > If Dash is fixed, then it's non-broken
> 
> Even if a fix goes upstream today, people will still be using a distro
> with the broken Dash for years, literally.  That’s why I think we have
> to cope with it.

Then it could be fixed in that distro?  And if the distro intentionally
keeps it broken for years, then that seems more a problem in the distro
than Guix to me.

Greetings,
Maxime.

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bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[paren--- via Bug reports for GNU Guix]

On Tue Jun 28, 2022 at 11:38 AM BST, Maxime Devos wrote:
> Then it could be fixed in that distro?  And if the distro intentionally
> keeps it broken for years, then that seems more a problem in the distro
> than Guix to me.

I believe Ludo' is referring to LTS distros and other situations where
somebody might not update for a long time.

    -- (

bug#51466: bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Maxime Devos]

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( schreef op di 28-06-2022 om 17:57 [+0100]:
> On Tue Jun 28, 2022 at 11:38 AM BST, Maxime Devos wrote:
> > Then it could be fixed in that distro?  And if the distro intentionally
> > keeps it broken for years, then that seems more a problem in the distro
> > than Guix to me.
> 
> I believe Ludo' is referring to LTS distros and other situations where
> somebody might not update for a long time.
> 
>     -- (

I'm thinking so too, though I want to mention LTS is not just ‘don't
update’ -- the third letter means ‘support’, which covers backporting
bug fixes, though I don't know if the distro would include dash > 9 fds
in this.

Greetings,
Maxime.

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bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Ludovic Courtès]

Hi,

"(" <paren@disroot.org> skribis:

> On Tue Jun 28, 2022 at 11:38 AM BST, Maxime Devos wrote:
>> Then it could be fixed in that distro?  And if the distro intentionally
>> keeps it broken for years, then that seems more a problem in the distro
>> than Guix to me.
>
> I believe Ludo' is referring to LTS distros and other situations where
> somebody might not update for a long time.

Yeah.  Whatever the reason, it’s a fact that our users might run Guix on
a system with a broken Dash, which is why I think we have to cope with it.

Ludo’.

bug#51466: bug#53355: guix shell --check: confusing error message

[bokr]

On +2022-06-27 12:17:08 +0200, Ludovic Courtès wrote:
> Hi Chris,
> 
> Chris Marusich <cmmarusich@gmail.com> skribis:
> 
> > It turns out that it is probably not OK to rely on shell redirection in
> > this case, after all.  For example, "dash does not support multi-digit
> > file descriptors":
> >
> > https://bugs.launchpad.net/ubuntu/+source/dash/+bug/249620
> 
> Bah.  :-/
> 
> [...]
> 
> > To resolve this, I changed the code so that it just writes to a
> > temporary file.  This is simple and more robust.  With the attached
> > patch, I was able to use a command like the one above to verify that
> > "guix environment --check" works correctly for Guix-built bash, dash,
> > ksh, fish, zsh, and ash.  I also verified that it works for Fedora's
> > /bin/sh and /bin/bash.
> >
> > What do you think of this file-based approach?  Supporting many
> > different shells is pretty tricky, but I think this patch does a good
> > enough job.
> 
> Like Maxime, I’d rather not create a temporary file.
> 
> I agree that Dash should be fixed, but in the meantime, we still want
> our stuff to work with the broken Dash (it’s the default on
> Debian/Ubuntu, isn’t it?).
> 
> I don’t have a better idea to offer though…
> 
> Ludo’.
> 
> 
>
If this is all about capturing an environment as text,
how about

--8<---------------cut here---------------start------------->8---
xargs -0 < /proc/$$/environ
--8<---------------cut here---------------end--------------->8---

(not limited to $$ I would think)
--
Regards,
Bengt Richter

bug#51466: bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Bengt Richter]

On +2022-06-27 13:23:15 +0200, bokr@bokr.com wrote:
> >
> If this is all about capturing an environment as text,
> how about
> 
> --8<---------------cut here---------------start------------->8---
> xargs -0 < /proc/$$/environ
> --8<---------------cut here---------------end--------------->8---
> 
> [...]
>
Actually, why fight shell stuff when guile can read it?
Or are these modules not available in your context?
--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> (use-modules (ice-9 textual-ports))
scheme@(guile-user)> (define ep (open-input-file "/proc/12430/environ"))
scheme@(guile-user)> (define es (get-string-all ep))
--8<---------------cut here---------------end--------------->8---
es from above got it all, when I tried manually as above.

FWIW I also did the same with (use-modules (rnrs bytevectors))
and the nulls show up as the expected zeroes.
--
Regards,
Bengt Richter